/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.lucene.analysis.en;

/*
 *
 *  Porter stemmer in Java. The original paper is in
 *
 *      Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,
 *      no. 3, pp 130-137,
 *
 *  See also https://snowballstem.org/algorithms/porter/stemmer.html
 *
 *  Bug 1 (reported by Gonzalo Parra 16/10/99) fixed as marked below.
 *  The words 'aed', 'eed', 'oed' leave k at 'a' for step 3, and b[k-1]
 *  is then out outside the bounds of b.
 *
 *  Similarly,
 *
 *  Bug 2 (reported by Steve Dyrdahl 22/2/00) fixed as marked below.
 *  'ion' by itself leaves j = -1 in the test for 'ion' in step 5, and
 *  b[j] is then outside the bounds of b.
 *
 *  Release 3.
 *
 *  [ This version is derived from Release 3, modified by Brian Goetz to
 *    optimize for fewer object creations.  ]
 *
 */

import org.apache.lucene.util.ArrayUtil;

/**
 * Stemmer, implementing the Porter Stemming Algorithm
 *
 * <p>The Stemmer class transforms a word into its root form. The input word can be provided a
 * character at time (by calling add()), or at once by calling one of the various stem(something)
 * methods.
 */
class PorterStemmer {
  private char[] b;
  private int i, /* offset into b */ j, k, k0;
  private boolean dirty = false;
  private static final int INITIAL_SIZE = 50;

  public PorterStemmer() {
    b = new char[INITIAL_SIZE];
    i = 0;
  }

  /**
   * reset() resets the stemmer so it can stem another word. If you invoke the stemmer by calling
   * add(char) and then stem(), you must call reset() before starting another word.
   */
  public void reset() {
    i = 0;
    dirty = false;
  }

  /**
   * Add a character to the word being stemmed. When you are finished adding characters, you can
   * call stem(void) to process the word.
   */
  public void add(char ch) {
    if (b.length <= i) {
      b = ArrayUtil.grow(b, i + 1);
    }
    b[i++] = ch;
  }

  /**
   * After a word has been stemmed, it can be retrieved by toString(), or a reference to the
   * internal buffer can be retrieved by getResultBuffer and getResultLength (which is generally
   * more efficient.)
   */
  @Override
  public String toString() {
    return new String(b, 0, i);
  }

  /** Returns the length of the word resulting from the stemming process. */
  public int getResultLength() {
    return i;
  }

  /**
   * Returns a reference to a character buffer containing the results of the stemming process. You
   * also need to consult getResultLength() to determine the length of the result.
   */
  public char[] getResultBuffer() {
    return b;
  }

  /* cons(i) is true <=> b[i] is a consonant. */

  private final boolean cons(int i) {
    switch (b[i]) {
      case 'a':
      case 'e':
      case 'i':
      case 'o':
      case 'u':
        return false;
      case 'y':
        return (i == k0) ? true : !cons(i - 1);
      default:
        return true;
    }
  }

  /* m() measures the number of consonant sequences between k0 and j. if c is
   *  a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
   *  presence,
   *
   *       <c><v>       gives 0
   *       <c>vc<v>     gives 1
   *       <c>vcvc<v>   gives 2
   *       <c>vcvcvc<v> gives 3
   *       ....
   */

  private final int m() {
    int n = 0;
    int i = k0;
    while (true) {
      if (i > j) return n;
      if (!cons(i)) break;
      i++;
    }
    i++;
    while (true) {
      while (true) {
        if (i > j) return n;
        if (cons(i)) break;
        i++;
      }
      i++;
      n++;
      while (true) {
        if (i > j) return n;
        if (!cons(i)) break;
        i++;
      }
      i++;
    }
  }

  /* vowelinstem() is true <=> k0,...j contains a vowel */

  private final boolean vowelinstem() {
    int i;
    for (i = k0; i <= j; i++) if (!cons(i)) return true;
    return false;
  }

  /* doublec(j) is true <=> j,(j-1) contain a double consonant. */

  private final boolean doublec(int j) {
    if (j < k0 + 1) return false;
    if (b[j] != b[j - 1]) return false;
    return cons(j);
  }

  /* cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
   *  and also if the second c is not w,x or y. this is used when trying to
   *  restore an e at the end of a short word. e.g.
   *
   *       cav(e), lov(e), hop(e), crim(e), but
   *       snow, box, tray.
   *
   */

  private final boolean cvc(int i) {
    if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2)) return false;
    else {
      int ch = b[i];
      if (ch == 'w' || ch == 'x' || ch == 'y') return false;
    }
    return true;
  }

  private final boolean ends(String s) {
    int l = s.length();
    int o = k - l + 1;
    if (o < k0) return false;
    for (int i = 0; i < l; i++) if (b[o + i] != s.charAt(i)) return false;
    j = k - l;
    return true;
  }

  /* setto(s) sets (j+1),...k to the characters in the string s, readjusting
  k. */

  void setto(String s) {
    int l = s.length();
    int o = j + 1;
    for (int i = 0; i < l; i++) b[o + i] = s.charAt(i);
    k = j + l;
    dirty = true;
  }

  /* r(s) is used further down. */

  void r(String s) {
    if (m() > 0) setto(s);
  }

  /* step1() gets rid of plurals and -ed or -ing. e.g.
   *
   *        caresses  ->  caress
   *        ponies    ->  poni
   *        ties      ->  ti
   *        caress    ->  caress
   *        cats      ->  cat
   *
   *        feed      ->  feed
   *        agreed    ->  agree
   *        disabled  ->  disable
   *
   *        matting   ->  mat
   *        mating    ->  mate
   *        meeting   ->  meet
   *        milling   ->  mill
   *        messing   ->  mess
   *
   *        meetings  ->  meet
   *
   */

  private final void step1() {
    if (b[k] == 's') {
      if (ends("sses")) k -= 2;
      else if (ends("ies")) setto("i");
      else if (b[k - 1] != 's') k--;
    }
    if (ends("eed")) {
      if (m() > 0) k--;
    } else if ((ends("ed") || ends("ing")) && vowelinstem()) {
      k = j;
      if (ends("at")) setto("ate");
      else if (ends("bl")) setto("ble");
      else if (ends("iz")) setto("ize");
      else if (doublec(k)) {
        int ch = b[k--];
        if (ch == 'l' || ch == 's' || ch == 'z') k++;
      } else if (m() == 1 && cvc(k)) setto("e");
    }
  }

  /* step2() turns terminal y to i when there is another vowel in the stem. */

  private final void step2() {
    if (ends("y") && vowelinstem()) {
      b[k] = 'i';
      dirty = true;
    }
  }

  /* step3() maps double suffices to single ones. so -ization ( = -ize plus
  -ation) maps to -ize etc. note that the string before the suffix must give
  m() > 0. */

  private final void step3() {
    if (k == k0) return; /* For Bug 1 */
    switch (b[k - 1]) {
      case 'a':
        if (ends("ational")) {
          r("ate");
          break;
        }
        if (ends("tional")) {
          r("tion");
          break;
        }
        break;
      case 'c':
        if (ends("enci")) {
          r("ence");
          break;
        }
        if (ends("anci")) {
          r("ance");
          break;
        }
        break;
      case 'e':
        if (ends("izer")) {
          r("ize");
          break;
        }
        break;
      case 'l':
        if (ends("bli")) {
          r("ble");
          break;
        }
        if (ends("alli")) {
          r("al");
          break;
        }
        if (ends("entli")) {
          r("ent");
          break;
        }
        if (ends("eli")) {
          r("e");
          break;
        }
        if (ends("ousli")) {
          r("ous");
          break;
        }
        break;
      case 'o':
        if (ends("ization")) {
          r("ize");
          break;
        }
        if (ends("ation")) {
          r("ate");
          break;
        }
        if (ends("ator")) {
          r("ate");
          break;
        }
        break;
      case 's':
        if (ends("alism")) {
          r("al");
          break;
        }
        if (ends("iveness")) {
          r("ive");
          break;
        }
        if (ends("fulness")) {
          r("ful");
          break;
        }
        if (ends("ousness")) {
          r("ous");
          break;
        }
        break;
      case 't':
        if (ends("aliti")) {
          r("al");
          break;
        }
        if (ends("iviti")) {
          r("ive");
          break;
        }
        if (ends("biliti")) {
          r("ble");
          break;
        }
        break;
      case 'g':
        if (ends("logi")) {
          r("log");
          break;
        }
    }
  }

  /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */

  private final void step4() {
    switch (b[k]) {
      case 'e':
        if (ends("icate")) {
          r("ic");
          break;
        }
        if (ends("ative")) {
          r("");
          break;
        }
        if (ends("alize")) {
          r("al");
          break;
        }
        break;
      case 'i':
        if (ends("iciti")) {
          r("ic");
          break;
        }
        break;
      case 'l':
        if (ends("ical")) {
          r("ic");
          break;
        }
        if (ends("ful")) {
          r("");
          break;
        }
        break;
      case 's':
        if (ends("ness")) {
          r("");
          break;
        }
        break;
    }
  }

  /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */

  private final void step5() {
    if (k == k0) return; /* for Bug 1 */
    switch (b[k - 1]) {
      case 'a':
        if (ends("al")) break;
        return;
      case 'c':
        if (ends("ance")) break;
        if (ends("ence")) break;
        return;
      case 'e':
        if (ends("er")) break;
        return;
      case 'i':
        if (ends("ic")) break;
        return;
      case 'l':
        if (ends("able")) break;
        if (ends("ible")) break;
        return;
      case 'n':
        if (ends("ant")) break;
        if (ends("ement")) break;
        if (ends("ment")) break;
        /* element etc. not stripped before the m */
        if (ends("ent")) break;
        return;
      case 'o':
        if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't')) break;
        /* j >= 0 fixes Bug 2 */
        if (ends("ou")) break;
        return;
      /* takes care of -ous */
      case 's':
        if (ends("ism")) break;
        return;
      case 't':
        if (ends("ate")) break;
        if (ends("iti")) break;
        return;
      case 'u':
        if (ends("ous")) break;
        return;
      case 'v':
        if (ends("ive")) break;
        return;
      case 'z':
        if (ends("ize")) break;
        return;
      default:
        return;
    }
    if (m() > 1) k = j;
  }

  /* step6() removes a final -e if m() > 1. */

  private final void step6() {
    j = k;
    if (b[k] == 'e') {
      int a = m();
      if (a > 1 || a == 1 && !cvc(k - 1)) k--;
    }
    if (b[k] == 'l' && doublec(k) && m() > 1) k--;
  }

  /** Stem a word provided as a String. Returns the result as a String. */
  public String stem(String s) {
    if (stem(s.toCharArray(), s.length())) return toString();
    else return s;
  }

  /**
   * Stem a word contained in a char[]. Returns true if the stemming process resulted in a word
   * different from the input. You can retrieve the result with getResultLength()/getResultBuffer()
   * or toString().
   */
  public boolean stem(char[] word) {
    return stem(word, word.length);
  }

  /**
   * Stem a word contained in a portion of a char[] array. Returns true if the stemming process
   * resulted in a word different from the input. You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem(char[] wordBuffer, int offset, int wordLen) {
    reset();
    if (b.length < wordLen) {
      b = new char[ArrayUtil.oversize(wordLen, Character.BYTES)];
    }
    System.arraycopy(wordBuffer, offset, b, 0, wordLen);
    i = wordLen;
    return stem(0);
  }

  /**
   * Stem a word contained in a leading portion of a char[] array. Returns true if the stemming
   * process resulted in a word different from the input. You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem(char[] word, int wordLen) {
    return stem(word, 0, wordLen);
  }

  /**
   * Stem the word placed into the Stemmer buffer through calls to add(). Returns true if the
   * stemming process resulted in a word different from the input. You can retrieve the result with
   * getResultLength()/getResultBuffer() or toString().
   */
  public boolean stem() {
    return stem(0);
  }

  public boolean stem(int i0) {
    k = i - 1;
    k0 = i0;
    if (k > k0 + 1) {
      step1();
      step2();
      step3();
      step4();
      step5();
      step6();
    }
    // Also, a word is considered dirty if we lopped off letters
    // Thanks to Ifigenia Vairelles for pointing this out.
    if (i != k + 1) dirty = true;
    i = k + 1;
    return dirty;
  }
}
